1. Field of the Invention
The present invention relates to an adjust screw device for a carburetor of an internal combustion engine to be installed on an automobile or the like, and more particularly to an adjust screw device for a carburetor, by which the exhaust gas cleaning function intrinsically incorporated in the automobile or the like is ensured by limiting the range within which the automobile user can adjust an idle R.P.M. adjusting screw.
2. Description of the Prior Art
A carburetor has conventionally been equipped with an adjust screw partly for presetting the idle R.P.M. of an internal combustion engine and partly for adjusting the idle R.P.M. which has been changed due to the aging during the using process. This adjust screw is mounted, for example, on a stationary bracket which is positioned in the vicinity of the throttle lever of the carburetor, and has its leading end abutting against the throttle lever. A throttle lever shaft is fixed to the throttle lever at a position which is eccentric from the abutting position between the throttle lever and the leading end of the adjust screw. As a result, by rotating the adjust screw so that it moves toward or away from the throttle lever, the throttle lever is moved so that a throttle valve in the carburetor is rotated by the throttle lever shaft. In other words, the idle R.P.M. of an automotive engine can be preset at a desired value by rotating the adjust screw back and forth.
However, since the adjust screw has its head exposed to the outside, the user of the automobile, for example, can readjust the opening of the throttle valve freely up to an unnecessary range, and the exhaust gas cleaning function intrinsically incorporated in the automobile may resultantly be deteriorated to a considerable extent by that readjustment.